Recent advances in technology have led to a dramatic growth in network-based video applications. Video transmission over unreliable and error-prone wireless channel is one of the major challenges for wireless video applications. Due to the predictive coding and variable length coding, the compressed video is extremely sensitive to transmission errors. Video transmission over wireless networks suffers from packet loss due to either temporary packet drop or fading-induced bit errors. Therefore, the video applications have to provide sufficient robustness to ensure that the quality of the decoded video is not overly affected by the channel unreliability.
To deliver better quality video given a limited bandwidth, the challenging issue is to minimize the effect of packet loss while bringing little impact on bandwidth efficiency. Forward error correction (FEC) is broadly used to combat transmission errors. However, it consumes additional bits, which compromises coding efficiency. To achieve robustness without much loss in bandwidth efficiency, interleaving, a traditional approach in channel coding to mitigate the effect of burst errors, has been investigated. Interleaving schemes focus on dispersing the error distributions to facilitate error concealment. Error concealment mechanisms are typically more efficient if the damaged regions are small. For an instance, compared to smaller number of large errors, larger number of small erroneous regions distributed uniformly over the video bit-stream in both spatial and temporal dimensions usually result in better visual quality. Flexible Macroblock Ordering (FMO) is an interleaving tool introduced in H.264/AVC. It enables partition of a picture into slice groups, with each slice becoming an independently decodable subset of a slice group. The use of FMO, where spatial interleaving is explored, has been investigated. However, spatial interleaving may lead to dramatic decrease in coding efficiency. Besides, the errors can only be distributed spatially. To at least increase coding efficiency, temporal interleaving has been studied. However, the interleaving pattern is defined in a heuristic manner and the solution could not be generalized for any target number of packets.
Thus it is an object of the present invention to address at least the problems mentioned above and to provide methods and apparatus of packetizing data for improving the error robustness of the transmitted video without extra redundancy, which is highly desirable for bandwidth-limited networks.